1. Field of the Invention
This invention relates broadly to orthopedic fixation devices. More particularly, this invention relates to threaded pins for treatment of fractures, particularly of the distal radius bone.
2. State of the Art
Treatment of bone fractures, and particularly distal radius fractures, depends on the type of fracture. In a distal radius, Type I fractures include an undisplaced non-articular fracture of the distal radius that defines a distal radius fragment. Type I fractures do not require reduction or are stable post-reduction. Type II fractures include a medial/lateral or volar/dorsal non-articular displaced fracture which also defines a distal radius fragment. Type II fractures are reducible closed, but remain unstable.
Type I fractures are typically treated with casting. Casting provides immobilization and the traditional immobilization period is six to eight weeks, followed by a course of physiotherapy to restore range of motion. The length of the immobilization and the resulting loss of range of motion is undesirable to many patients, including athletes, artists, musicians, and patients with an economic urgency to return to work.
Current treatment of Type II fractures includes inserting a threaded pin across the fracture. However, pin implantation is not always entirely successful. One drawback with many threaded pins in treating distal radius fractures is that their blunt tips will not always engage the radius shaft cortex and will slide into the intramedullary canal, thereby limiting the amount of proximal purchase of the pin. This is a particular concern with fractures of older osteoporotic bone. In these patients, better purchase would allow more aggressive physiotherapy. In addition, the threaded fixation pins adapted for treatment of distal radius fractures are available in a single length and thus need to be cut after insertion. The cut ends of the pins interfere with early range of motion and, to a limited extent, irritate the subcutaneous tissue and may interfere with extensor tendon function. Moreover, as the pins protrude above the bone surface, a second operation is require to remove the pins.